The present invention relates to a process for the purification of olefine oxides. More particularly, it relates to the purification of the olefine oxides obtained by epoxidising the corresponding olefines with peroxide compounds.
In the epoxidation of olefines with peroxide compounds, such as hydrogen peroxide or percarboxylic acids, olefine oxides containing various impurities, such as water, glycols, aldehydes, alcohols, unreacted olefine and the solvent which may have been used, are obtained at the outlet of the epoxidation reactor or after preliminary rectification. Some of these products, which prove troublesome when the olefine oxides are used, for example, as a monomer for the manufacture of polymers, are very difficult to remove by the conventional distillation techniques. Moreover, during the numerous distillation steps required for their removal, the formation of large amounts of by-products, such as esters and glycols, is observed.
Thus, in the manufacture of propylene oxide by epoxidising propylene with an organic solution of a peracid (Belgian Pat. No. 847,664, filed on Oct. 27, 1976 in the name of Bayer AG and Degussa), propylene glycol is formed during the steps for separating the reaction mixture into its various constituents.
In order to remove the esters present in propylene oxide, it has been proposed (Japanese Patent Application No. 47/18,812, filed on Feb. 16, 1971 in the name of Mitsubishi Chem. Ind. LTD.) to treat the propylene oxide in a distillation column in the presence of an aqueous solution of a saponifying agent. However, this technique exhibits the disadvantage that it causes considerable corrosion in the still-of the distillation column.